Spectroscopic diagnostic method and system based on scattering of polarized light

Abstract

The present invention provides systems and methods for the determination of the physical characteristics of a structured superficial layer of material using light scattering spectroscopy. The light scattering spectroscopy system comprises optical probes that can be used with existing endoscopes without modification to the endoscope itself. The system uses a combination of optical and computational methods to detect physical characteristics such as the size distribution of cell nuclei in epithelial layers of organs. The light scattering spectroscopy system can be used alone, or in conjunction with other techniques, such as fluorescence spectroscopy and reflected light spectroscopy.

1 . A light scattering spectroscopic system comprising:
 an optical probe comprising:
 an illumination optical fiber; 
 a first collection optical fiber oriented at a first angle relative to a probe axis; and 
 a second collection optical fiber oriented at a second angle relative 
   to the probe axis status different from the first angle; and
 a polarizer; 
   a broadband light source optically coupled to the illumination optical fiber;   a detector system optically coupled to the first collection optical fiber and the second collection optical fiber, the detector system generating a spectrum from light transmitted by at least one of the first or second collection fibers to the detector system; and   a data processor in communication with the detector system.   
     
     
         2 . The system of  claim 1 , wherein the optical probe further comprises one or more excitation illumination optical fibers optically coupled to the light source. 
     
     
         3 . The system of  claim 2 , wherein the illumination optical fiber transmits corrected broadband illumination and the one or more excitation illumination optical fibers transmit light having a wavelength in the range from about 300 nm to about 460 nm. 
     
     
         4 . The system of  claim 1 , wherein the optical probe comprises:
 a first illumination optical fiber optically coupled to the light source and adapted to transmit a first wavelength of light in the range from about 300 nm to about 460 nm; and   a second illumination optical fiber optically coupled to the light source and adapted to transmit a second wavelength of light in the range from about 300 nm to about 460 nm, the a second wavelength of light different from the first wavelength of light.   
     
     
         5 . The system of  claim 1 , wherein light emitted in response to a first wavelength of light in the range from about 300 nm to about 460 nm and light emitted in response to a second wavelength of light in the range from about 300 nm to about 460 nm, the second wavelength of light being different from the first wavelength of light, are transmitted through separate collection optical fibers. 
     
     
         6 . The system of  claim 1 , wherein the optical probe further comprises one or more emitted light collection optical fibers optically coupled to the detector system. 
     
     
         7 . The system of  claim 6 , wherein one or more of the one or more emitted light collection optical fibers transmit light in the wavelength range from about 335 nm to about 700 nm. 
     
     
         8 . The system of  claim 1 , wherein the optical probe further comprises a second polarizer. 
     
     
         9 . The system of  claim 8 , wherein the optical probe comprises at least two polarizers, wherein a polarization axis of one polarizer is substantially orthogonal to a polarization axis of another polarizer. 
     
     
         10 . The system of  claim 1 , wherein the collection optical fibers have a proximal end optically coupled to the detector system and a distal end, wherein one or more polarizers are positioned at the distal end. 
     
     
         11 . The system of  claim 1 , wherein the light source comprises a mercury lamp. 
     
     
         12 . The system of  claim 1 , wherein the light source comprises a xenon lamp. 
     
     
         13 . The system of  claim 1 , wherein the detector system comprises a charge coupled device. 
     
     
         14 . The system of  claim 1 , wherein the detector system comprises a holographic grating. 
     
     
         15 . The system of  claim 1 , wherein the detector system comprises a phase locked shutter. 
     
     
         16 . The system of  claim 1 , wherein the data processor stores instructions to determine a particle characteristic based at least in part on one or more spectra generated by the detector system. 
     
     
         17 . The system of  claim 19 , wherein the particle characteristic is a particle size distribution. 
     
     
         18 . The system of  claim 1 , wherein the data processor stores instructions to subtract a spectrum acquired from a collection optical fiber oriented to collect light polarized parallel to a plane of polarization of the illumination light from a spectrum acquired from a collection optical fiber oriented to collect light polarized perpendicular to the plane of polarization of the illumination light. 
     
     
         19 . The system of  claim 1  wherein the detector system comprises a pixellated image sensor. 
     
     
         20 . The system of  claim 1  wherein the data processor determines a periodic component of detected light as a function of wavelength to determine a physical characteristic of tissue illuminated with the illumination fiber. 
     
     
         21 . The system of  claim 1  wherein the detector detects one or more of a light scattering spectrum, a reflectance spectrum and a fluorescence spectrum. 
     
     
         22 . The system of  claim 1  further comprising a filter wheel. 
     
     
         23 . The system of  claim 1  further comprising a shutter wheel. 
     
     
         24 . The system of  claim 1  a plurality of excitation fibers, a plurality of fluorescence collecting fibers on a reflectance collecting fiber. 
     
     
         25 . The system of  claim 1  wherein the data processor processes a first collected polarization component and a second collected polarization component to obtain a difference spectrum. 
     
     
         26 . The system of  claim 1  further comprising a retainer holding the collection fibers and the illumination fiber. 
     
     
         27 . The system of  claim 1  wherein the processor determines a frequency spectrum with a Fourier transform. 
     
     
         28 . The system of  claim 1  wherein the date processor determines normal from dysplastic or cancerous tissue. 
     
     
         29 . The system of  claim 2  further comprising and imaging detector at a distal end of the probe and a fluorescence spectrometer that is optically coupled to a distal end of the probe with an additional optical fiber or fiber bundle. 
     
     
         30 . An optical probe comprising:
 a probe housing having a proximal and a distal end, the proximal end of the probe housing being adapted for optical connection to a light source;   a plurality of optical fibers positioned about at least one inner optical fiber that is positioned within said housing, the optical fibers being bound together at the distal end of said optical fibers to form a retainer module with a polished distal surface;   at least one polarizer; and   an optical shield enclosing the distal end of said probe housing, the optical shield being positioned distal to the retainer module and adapted to provide a light transmitting enclosure for the optical probe, the distal surface of the optical shield being suitable for contact with a surface.   
     
     
         31 . The optical probe of  claim 30 , wherein the distal ends of the optical fibers are bonded in an array. 
     
     
         32 . The optical probe of  claim 30 , wherein the retainer module comprises an adhesive that bonds the optical fibers into an array. 
     
     
         33 . The optical probe of  claim 30 , wherein the plurality of optical fibers are bound together in a circular array around a longitudinal axis of one of the at least one inner optic fiber. 
     
     
         34 . The optical probe of  claim 30 , wherein the longitudinal axes of the plurality of optical fibers are at an angle in the range from about 2 degrees to about 6 degrees with respect to a longitudinal axis of one of the at least one inner optical fiber. 
     
     
         35 . The optical probe of  claim 30 , wherein the at least one inner optical fiber is held on a longitudinal axis of the probe housing by an axial hole in a tappered plug. 
     
     
         36 . The optical probe of  claim 30 , wherein the plurality of optical fibers positioned about the at least one inner optical fiber are held at an angle in the range from about 2 degrees to about 6 degrees with respect to a longitudinal axis of one of the at least one inner optical fiber by a tappered bore in the probe housing. 
     
     
         37 . A method of analyzing spectral data to determining a characteristic of a structure in a layer of tissue comprising:
 providing a light collection system that collects fluorescent and reflected light from the tissue at a plurality of wavelengths and detects the collected light;   forming a fluorescence representation and a scattered light representation as a function of wavelength from the detected light; and   determining a characteristic of a structure of the tissue layer using the fluorescence representation and the scattered light representation.   
     
     
         38 . The method of  claim 37  further comprising the step of forming a reflectance representation. 
     
     
         39 . A method of determining a characteristic of a tissue layer comprising:
 directing a polarized light onto a region of interest of the tissue layer;   acquiring light backscattered from the region of interest tissue with a first collection optical fiber disposed at a first angle;   acquiring light backscattered from the region of interest tissue with a second collection optical fiber disposed at a second angle different from the first angle; and   determining a characteristic of the region of interest based at least in part on the light acquired by both the first collection optical fiber and the second collection optical fiber.   
     
     
         40 . The method of  claim 39 , wherein the tissue layer comprises an epithelial layer and the step of determining a characteristic comprises determining a characteristic of the epithelial layer. 
     
     
         41 . The method of  claim 39 , wherein the tissue layer characteristic comprises the size of a structure within the region of interest. 
     
     
         42 . The method of  claim 41 , wherein the structure is the nuclei of epithelial cells in the region of interest. 
     
     
         43 . The method of  claim 39 , further comprising the steps of:
 directing a first excitation light onto the region of interest; and   acquiring a first fluorescence from the region of interest in response to the first excitation light with a third collection optical fiber;   determining a characteristic of the region of interest based at least in part on the light acquired by the first collection optical fiber, the a second collection optical fiber and the third collection optical fiber.   
     
     
         44 . The method of  claim 43 , further comprising the steps of:
 directing a second excitation light onto the region of tissue; an   acquiring a second fluorescence from the tissue in response to the second excitation light with a fourth collection optical fiber;   determining a characteristic of the region of interest based at least in part on the light acquired by the first collection optical fiber, the second collection optical fiber, the third collection optical fiber, and the fourth collection optical fiber.   
     
     
         45 . The method of  claim 39 , wherein the step of determining the tissue characteristic comprises:
 generating a backscatter spectrum from the light acquired by both the first collection optical fiber and the second collection optical fiber; and   determining a characteristic of the region of interest based at least in part on the backscatter spectrum.   
     
     
         46 . The method of  claim 43 , wherein the step of determining the tissue characteristic comprises:
 generating a first fluorescence spectrum from the light acquired from the tissue in response to the first excitation light; and   determining a characteristic of the tissue based at least in part on the first fluorescence spectrum.   
     
     
         47 . The method of  claim 44 , wherein the step of determining a characteristic tissue comprises:
 generating a first fluorescence spectrum from the light acquired from the tissue in response to the first excitation light;   generating a second fluorescence spectrum from the light acquired from the tissue in response to the second excitation light;   generating a backscatter spectrum from the light acquired by both the first collection optical fiber and the second collection optical fiber   generating a reflectance spectrum from the light acquired by both the first collection optical fiber and the second collection optical fiber.   determining a characteristic of the region of interest based at least in part on the first fluorescence spectrum, the second fluorescence spectrum, the backscatter spectrum and the reflectance spectrum.   
     
     
         48 . The method of  claim 46 , wherein the tissue characteristic comprises tissue dysplasia. 
     
     
         49 . The method of  claim 47 , wherein the tissue characteristic comprises tissue dysplasia. 
     
     
         50 . The method of  claim 47 , wherein the determining a characteristic of the region of interest comprises determining an intrinsic fluorescence spectrum by correcting at least one of the first fluorescence spectrum and second fluorescence spectrum using the reflectance spectrum.